Screening, Identification and Fermentation Conditions Optimization of Antagonistic Strain 6-59 of Bacillus megaterium against Ceratosphaeria phyllostachydis The Relationship between Occurrence of the Dieback Blight of Phyllostachys pubescens and Stand Growth and Site Conditions Optimization of spore formation conditions for antagonistic strain 6-59 of Bacillus megaterium against Ceratosphaeria phyllostachydis